[RFC PATCH 02/28] cli: Add LIL shell

[Sean Anderson]

On 7/2/21 9:33 AM, Sean Anderson wrote:
> On 7/2/21 7:03 AM, Wolfgang Denk wrote:
>> Dear Sean,
>>
>> In message <20210701061611.957918-3-seanga2 at gmail.com> you wrote:
>>> This is the LIL programming language [1] as originally written by Kostas
>>> Michalopoulos <badsector at runtimeterror.com>. LIL is a stripped-down TCL
>>> variant. Many syntax features are very similar to shell:
>>
>> Do you have a list of the exact differencec between LIL and a
>> standard shell?
> 
> For a partial list, see
> 
> [1] https://github.com/Forty-Bot/lil/commits/master

Whoops, looks like I completely misread what you were asking here. I
don't have an exhaustive list of differences, but here are some similar
things expressed in both languages:

sh				tcl

foo=bar				set foo bar
echo $foo			echo $foo

if [ 1 -gt 2 ]; then		if {1 > 2} {
	echo a				echo a
else				} {
	echo b				echo b
fi				}

foo() {				proc foo {first second} {
	echo $1 $2			echo $first $second
}				}

for file in $(ls *.c); do	foreach file [glob *.c] {
	echo $file			echo $file
done				}

fact() {
	if [ $1 -eq 0 ]; then
		echo 1
	else
		echo $(($1 * $(fact $(($1 - 1)))))
	fi
}

				proc fact {n} {
					if {$n} {
						expr {$n * [fact [expr {$n - 1}]]}
					} {
						return 1
					}
				}

Hopefully this gives you a bit of a feel for the basic differences.

--Sean

> 
>> I wonder, if we deviate from standard shell syntax anyway, we could
>> also have a look at lua, for example?
> 
> I also looked at lua (see the cover letter), but I rejected it based on
> size constraints (eLua was around the size of U-Boot itself).
> 
> Because of how often the shell is used to debug things, I wanted the
> candidate I picked to have similar syntax to the existing shell. For
> example,
> 
>      load mmc ${mmcdev}:${mmcpart} $loadaddr $image
> 
> is a valid command in both Hush and LIL. Compare with lua, which might
> express the above as
> 
>      load("mmc", mmcdev .. ":" .. mmcpart, loadaddr, image)
> 
> which I think is a much larger deviation from existing syntax.
> 
> --Sean